Lifting and loading means



July 9, 1963 J. c. MARTIN 3,097,009

LIFTING AND LOADING MEANS Filed Oct. 19, 1960 4 Sheets-Sheet 1 INVENTOR JOHN C. MART/N July 9, 1963 J. c. MARTIN 3,097,009

LIFTING AND LOADING MEANS Filed Oct. 19, 1960 Sheets-Sheet 2 INVENTOR JOHN C. MART/N July 9, 1963 J. c. MARTIN LIFTING AND LOADING MEANS 4 Sheets-Sheet 3 Filed Oct. 19, 1960 INVENTOI? 6 JOHN c. MARTIN WWW Am /w July 9, 1963 J. c. MARTIN LIFTING AND LOADING MEANS 4 Sheets-Sheet 4 Filed Oct. 19, 1960 INVENTOI? JOHN C. MARTIN arw fi ATTORNEYS United States Patent 3,07,009 LIFTING AND LOADING ldEANS John C. Martin, Toronto, Ontario, Canada, assignor to Diesel Equipment Limited, Toronto, Ontario, (Ianada Filed (Bet. 19, 1960, Ser. No. 63,567 Claims priority, application Great Britain Oct. 20, 1959 11 Claims. (til. 294--63) This invention relates to lifting and loading apparatus and in particular to a carrying element for engaging and locking a load. In one phase, the invention may be illustrated in relation to tines for lift forks.

Material handling by means of lift forks is commonly done in two ways. The lift fork tines either engage pallets on which the materials are placed or engage the materials themselves. For economic reasons it is preferable to eliminate the use of pallets and one instance where this has been found possible is in the handling of bricks. Whereas bricks were formerly stacked on pallets, and still are in some cases, it is now possible to pick up and carry a pile of bricks directly on the lift fork tines. This is done by stacking the bricks in a particular manner and using lift forks equipped with specially designed tines. The bricks are stacked so that the bottom layer has alternate rows of bricks only, leaving spaces for the reception of tines provided with gripping elements adapted to tightly grip the rows of bricks in the bottom layer whereby the whole stack may be raised. One known lift fork design for lifting and carrying bricks in the above mentioned manner has the tines of the lift fork rigidly fixed to the lift fork frame, and employs rotatable bars associated with each of the tines, which bars carry the gripping elements. When the weight of a stack of bricks is imposed on the tines a manually operated actuating mechanism mounted on the lift fork frame causes the bars to rotate whereby the gripping elements engage the bricks of the bottom layer. While this design has some merit, it suffers from several disadvantages and it is the purpose of this invention to overcome these disadvantages while retaining the merits of the known design.

One of the disadvantages above referred to stems from the principle of rigidly mounting the tines on the lift fork frame. This rigid mounting of the tines was deemed necessary to effect cooperation between the gripper element rods carried by the tines and the actuating mechanism for rotating the rods carried by the lift fork frame. However, it is generally recognized by those skilled in the art that the tines of lift forks should be removably con nected to the frame so that damaged tines may be readily replaced. Otherwise the whole lift fork assembly must be taken out of service in order to effect repair of the damaged tine. Furthermore, in certain circumstances it is advantages to be able to leave a set of tines in a load by disconnecting them from the lift fork frame. For example, where it is desired to move a load from one place to another by a series of intermediate steps, the set of tines first placed under the load may be left in place while the intermediate moves are effected by different lift fork frames being alternately engaged and disengaged with the one set of tines. Such an operation may be effected, by way of example, when moving a stack of bricks from a kiln by a fork lift truck to an elevator, from the elevator to a vehicle by means of a second fork lift truck and finally loading the vehicle by a lift fork loader atice tached to the vehicle. Such applications are not possible with the known design wherein the tines are rigidly fixed to the lift fork frame.

As mentioned above, the advantages of removable tines is generally recognized by those skilled in the art. However, prior to this invention, it was not possible .to combine this removable tine feature with the feature whereby the tines are provided with grippers which are automatically actuated as the weight of the stack of bricks is imposed on the tines.

It is the purpose of this invention to provide an improved lifting element capable along with another or other or such lifting elements of gripping and locking a load, which elements may be removable tines of a lifting fork or elements arranged in a lifting apparatus for performing a similar function.

The invention will be more fully understood by reference to the following sketches in which,

FIG. 1 is a perspective view of a lift fork in accordance with the invention.

FIG. 2 is a detail showing one end of a rotatable shaft of a gripper operating means.

FIG. 3 is a front view of the unit illustrated in FIG. 1 carrying a load of bricks.

FIG. 4 is a sectional side view of the unit shown in FIG. 1 carrying a load of bricks.

FIG. 5 is a fragmentary perspective view of an alternative tine in accordance with the invention.

FIG. 6 is a sectional plan view illustrating the operation of the tine of FIG. 5.

FIG. 7 is a schematic perspective of an alternative lifting unit having a plurality of independent lifting bars detachably connected to end frames for gripping and lifting a load.

The embodiment of the invention illustrated in FIG- URES 1-4 of the drawings comprises a lift fork assembly having a lifting frame 10 upon which a plurality of carrying members 12 in the form of tines are mounted :to support load with their longitudinal axes in parallel spaced apart relation. The tines 12 have a hooked upper end that engages with and pivots about the mounting bar 14. Adjacent their lower ends, the tines 12 engage with the bearing beam 16.

The tines can be mounted at any desired location laterally of the mounting bar and in some cases, it will be desirable to have locating means on the bar to space the tines laterally of the frame.

The tines 12 each have a series of grippers 18 which may be made of a durable rubber for the purpose of engaging and gripping material to be lifted between the tines as will be referred to later.

Tines 12 are capable of limited pivotal movement about the mounting bar 14 in response to the imposition of load thereon as will be fully described later and gripper operating means carried by the tines respond to this pivotal movement to operate the grippers 18 on each tine towards the grippers on an adjacent tine to grip material between adjacent tines.

The gripper operating means shown in FIGURES 14 comprises a lever 22 pivotally mounted on. the tine 12 as at 24 that has a cam surface 26 for engagement with the cam following lug 28 on the shaft 30. Shaft 30 is re tatably mounted with respect to the tine 12 adjacent each of its ends as at 32 and 34. A torsion rod 36 secured to the shaft 30 as at 33 adjacent one of its ends and secured to the tine 12 as at'39 adjacent its other end is biased to normally exert a twisting force on the shaft 30 that is transmitted to the lever 22 through the lug 28 to urge the lever in a counter-clockwise direction as viewed in FIGURE 4. Thus, when the tine is mounted in the lifting frame 10, the lever 22 engages with hearing beam 16 and maintains the tine spaced from the frame as at 40 when there is no load on the tine. The biasing force of the torsion rod 36 is thus sufficient to prevent its tine 12 from pivoting its full extent towards the frame 1%, when there is no load on the tine.

In use, asload is applied to the tine, the tine pivots with respect to the frame about the mounting bar 14 within the limits of the space 40 and the resulting counterclockwise movement of the tine with respect to bar 14 operates the lever 22 to turn the torsion rod 36 within its mounting to operate the grippers 18 that are mounted thereon outwardlyand towards grippers on an adjacent tine to cooperate therewith and grip materials that are disposed between them.

In FIGURES 3 and 4 the use of a lift fork assembly to raise a stack of bricks is illustrated. The bricks 42 are stacked above a lower strata formed in spaced apart rows 44 to permit the entry of the tines 12 therebetween. After the tineshave been inserted between the rows 44 they arelifted by means-of the frame 10. As the carrying surface of the tines engage withthe pile of bricks, they pivot with respect to the frame within limits of the space 40 and, as lug 28 moves along cam surface 26 shaft 30 rotates to actuate the gripping members 18 outwardly to engage with and grip rows 44 of the lower strata of bricks. Thus, as thepile of bricks is lifted upon the tines, the lower strata that is comprised of rows 44 is gripped by means of the outwardly moved grippers and carried along.

When the load is again dropped on to a floor and the weight relieved from the tines 12 the torsion rod 36 reasserts itself to turn the shaft 30 and pivot the tine about bar 14 in a clockwise direction to space the tine from the bearing beam 16 as at 40.

In FIGURES and 6, a tine having an alternative gripper operating means is shown. In this case, the tine which is fragmentarily illustrated is referred to by the numeral 50. The lever that engages with the frame when the tine is hung on the mounting bar 14 comprises a bar 52 that extends longitudinally of the tine 50 and has a roller '54 at its free end for engagement with the beam 16 of the frame. The lever 52 moves longitudinal- 1y of the tine when the tine pivots with respect to the frame in response to the application of load to the tine. It will be appreciated that the tine 50 has a hooked upper end similar tovthe tine 10 and engages with the bar 14 of the frame in the same fashion as the tine 10.

The-lever 52 is mounted with respect to its tine 59 by means of links 53 which pivotally connect with the tine as at 56 and pivotally connect with the lever as at 58. A spring 60 between the bracket '62 on the tine and the lug 64 on the lever 52.is normally compressed to bias the lever 52 to the rightas viewed in FIGURE 6 to maintain a spacing similar be the spacing 49' between the tine and the beam 16 when there is no load on the tines 50. As load is applied to the tines, it pivots with respect to the frame about the bar 14 to reduce the space 40 and move the lever '52 longitudinally of the tine against the pressure of spring 69.

As the lever 52 moves longitudinally of the tine as just aforesaid, it also moves laterally of the tine to carry the gripper members 66, which are directly mounted thereon, outwardly of the tineand towards the next adjacent tine. As adjacent gripping members are so moved outwardly bricks 68 .are gripped between adjacent tines.

It'will be appreciated that when load is reduced from the tines that the spring 60 will reassert itself to pivot the tine away from the frame and restore and maintain 4a the no load spacing between the frame and the tine. In FIGURE 6 the dotted line position of the lever52-is the no load position.

Alternatively, instead of employing carrying members as detachable tines of a lift fork assembly, they may be formed as individual bar units capable of connection with end frames employed for lifting a load.

FIGURE 7 is a cross sectional view showing an elongated carrying member 7 i), of which there are a plurality in parallel spaced relation, carried between end frames 72. The carrying members id are detachably mounted between support bars 74 in a similar manner to the manner in which the tines were mounted on the bar 14. The carrying members 70 each have a pivotally mounted lever 76 that engages with a bearing bar 7 8 and which is biased into contact therewith by means of a torsion rod 80 to maintain a spacing 82 between the carrying members 70 and the end frames 72. The grippers 84 are mounted on rotatably mounted shafts 86 and it will be apparent from the description thus far, that the operation of the grippers 84 is substantially the same as the operation already described of the grippers 18, the torsion bar'Si) being biased to maintain the spacing '82 when there. is no load on the. carrying members 7ft but to permit relative rotation ofthe carrying member and end frames with the imposition of load as the end frames assume a more vertical position to cause the gripping members to move outwardly and cooperate with each other to grip materials. The end frames 72 are, of course, raised together as indicated by the arrows in FIGURE 7. The gripping members release their grip as load is relieved from the holding members as the torsion members reassert themselves as explained above.

Other embodiments of the invention other than the ones illustrated will be apparent to those skilled in the art.

What I claim as my invention is:

1. A lifting device comprising a lifting frame, a series of elongated carrying members mountable in said frame to support a load with their longitudinal axes in parallel spaced apart relation, cooperating means on said frame, and said carrying members designed and constructed to mount said carrying members on said frame while allowing limited pivoting movement of said carrying members in relation to said frame about an axis perpendicular to F but spaced from the longitudinal axes of said carrying members in response to the imposition of load, said carrying members each having grippers, gripper operating means carried by each carrying member, responsive to pivoting movement of its respective carrying member about said axis under load for moving the grippers on each carrying member towards the grippers on an adjacent carrying member to co-operate therewith and grip materials between adjacent carrying members.

2. A lifting device as claimed in claim 1, in which said gripper operating means carried by each carrying member comprises a lever that engages with said frame when its respective carrying member is mounted in said frame as aforesaid, and means for biasing said lever towards the frame with a biasing force sufficient to prevent its carrying member and said frame from pivoting their full extent towards each other when there is no load on the carrying members, means for moving each said lever against the respective bias when its respective carrying member pivots under load, said biasing force having a magnitude that is overcome by the imposition of load on said carrying member to pivot the carrying member and frame with respect to each other, and thereby move the carrying member and lever with respect to each other, said lever being operably connected to said grippers.

3. A lifting device as claimed in claim 2, in which said lever is pivotally mounted on its respective carrying mem- .ber and in which said gripper operating means further include a shaft rotatably mounted on said carrying member, said grippers being mounted on said shaft, said shaft extending longitudinally of its respective carrying member, said lever having a cam surface, said shaft having a cam follower extending therefrom for engagement with the cam surface of said lever, whereby pivotal movement of said lever and carrying member with respect to each other is translated to rotation of said shaft.

4. A lifting device as claimed in claim 2, in which said lever is mounted for movement longitudinally of its respective carrying member in response to pivoting of the frames and carrying member as aforesaid.

5. A lifting device as claimed in claim 1, in which said carrying members are tines, said frame having a mounting bar, and a bearing beam underlying said mounting bar, said carrying members being mountable as aforesaid to pivot, as aforesaid, with respect to said mounting bar and to bear against said bearing beam.

6. A lifting device as claimed in claim 3, in which said means for biasing said lever towards said frame com prises a torsion bar stressed to exert a turning force on said rotatable shaft to force said cam follower into contact with said cam surface of said cam, said carrying members being tines, said frame having a mounting bar, and a bearing beam underlying said mounting bar, said carrying members being mountable as aforesaid to pivot, as aforesaid, with respect to said mounting bar and to bear against said bearing beam.

7. A lifting device as claimed in claim 2, in which said lever is mounted for movement longitudinally of its respective carrying member when said lever and carrying member pivot as aforesaid, said carrying members being tines, said frame having a mounting bar, and a bearing beam underlying said mounting bar, said carrying members being mountable as aforesaid to pivot, as aforesaid, with respect to said mounting bar and to bear against said bearing beam.

8. A lifting device comprising a lifting frame, a scrim of elongated carrying members mountable in said frame to support load with their longitudinal axes in parallel spaced apart relation, said frame and each of said carrying members being adapted for limited pivoting movement with respect to: each other about an axis substantially at right angles to, but spaced from the longitudinal axes of said carrying members in response to the imposi tion of load, said carrying members each having grippers, gripper operating means carried by each carrying member, responsive to pivotal movement of its respective carrying member and said frame as aforesaid, for operating the grippers on each carrying member towards the grippers on an adjacent carrying member to cooperate therewith and grip materials between adjacent carrying members, said gripper operating means including a lever that engages with said frame when its respective carrying member is mounted in said frame as aforesaid, means for biasing said lever towards the frame with a biasing force suflicient to prevent its carrying member and said frame from pivoting their full extent towards each other when there is no load on the carrying members, said biasing force having a magnitude that is overcome by the imposition of load on said carrying member to pivot the carrying member and frame with respect to each other, and thereby move the carrying member and lever with respect to each other, said lever being operably connected to said grippers, and pivotally mounted on its respective carrying member, said gripper operating means including a shaft rotatably mounted on said carrying member, said grippers being mounted on said shaft, said shaft extending longitudinally of its respective carrying member, said lever having a cam surface, said shaft having a cam follower extending therefrom for engagement with the cam surface of said lever, whereby pivotal movement of said lever and carrying member lever with respect to each other is translated to rotation of said shaft, said means for biasing said lever towards said frame comprising a torsion bar stressed to exert a turning force on said rotatable shaft to force said cam follower into contact with said cam surface of said lever.

9. A lifting device comprising a lifting frame, a series of elongated carrying members mountable in said frame to support load with their longitudinal axes in parallel spaced apart relation, said frame and each of said carrying members being adapted for limiting pivoting movement with respect to each other about an. axis substantially at right angles to, but spaced from the longitudinal axes of said carrying members in response to the imposition of load, said carrying members each having grippers, gripper operating means carried by each carrying member, responsive to pivotal movement of its respective carrying member and said frame as aforesaid, for operating the grippers on each carrying member towards the grippers on an adjacent carrying member to cooperate therewith and grip materials between adjacent carrying members, said gripper operating means including a lever that engages with said frame when its respective carrying member is mounted in said frame as aforesaid, means for biasing said lever towards the frame with a biasing force sufiicient to prevent its carrying member and said frame from pivoting their full extent towards each other when there is no load on the carrying members, said biasing force having a magnitude that is overcome by the imposition of load on said carrying member to pivot the carrying member and frame with respect to each other, and thereby move the carrying member and lever with respect to each other, said lever being operably connected to said grippers, said lever being mounted for movement longitudinally of its respective carrying member in response to pivoting of the frames and carrying member, said means for biasing said lever towards said frame comprising spring means connecting said lever and carrying member, and link means for mounting said lever on its respective carrying member, said link means pivotally connecting with said lever and with its respective carrying member and being adapted to move said lever laterally of its respective carrying member as it moves longitudinally thereof in response to pivoting of the frame and carrying member as aforesaid.

10. A lifting device as claimed in claim 9 in which said lever and grippers are operably connected as aforesaid by direct mounting of the grippers on the lever.

11. A lifting device comprising a lifting frame, a series of elongated carrying members mountable in said frame to support load with their longitudinal axes in parallel spaced apart relation, said frame and each of said carrying members being adapted for limited pivoting movement with respect to each other about an axis substantially at right angles to, but spaced from the longitudinal axes of said carrying members in response to the imposition of load, said carrying members each having grippers, gripper operating means carried by each carrying member, responsive to pivotal movement of its respective carrying member and said frame as aforesaid, for operating the grippers on each carrying member towards the grippers on an adjacent carrying member to cooperate therewith and grip materials between adjacent carrying members, said gripper operating means including a lever that engages with said frame when its respective carrying member is mounted in said frame as aforesaid, and means for biasing said lever towards the frame with a biasing force suflicient to prevent its carrying member and said frame from pivoting their full extent towards each other when there is no load on the carrying members, said biasing force having a magnitude that is overcome by the imposition of load on said carrying member to pivot the carrying member and frame with respect to each other, and thereby move the carrying member and lever with respect to each other, said lever being operably connected to said grippers, said lever being pivotally mounted on its respective carrying member and in which said gripper operating means further including a shaft rotatably mounted on said carrying member, said grip- 3,097,009 7 8 pers being mounted on said shaft, said shaft extending aforesaid, with respect to said mounting bar and to bear longitudinally of its respective carrying member, said against said bearing beam. lever having a cam surface, said shaft having a cam follower extending therefrom for engagement with the cam Refere e Ci i h fil f hi patent surface 0f said lever wb'ereby pivotal movement of said 5 v lever and carrying. member with respect to eachbther is UNITED STATES PATENTS translated to rotation of said shaft, said carrying mem- 2:530375 Cartwright 21, 1950 hers being-tines, said frame having a mounting bar, and a bearing beam underlying said mounting bar, said carry- FOREIGN PATENTS ing members being mountable as aforesaid to pivot, as 10 1,083,948 France June 30, 1954 

1. A LIFTING DEVICE COMPRISING A LIFTING FRAME, A SERIES OF ELONGATED CARRYING MEMBERS MOUNTABLE IN SAID FRAME TO SUPPORT A LOAD WITH THEIR LONGITUDINAL AXES IN PARALLEL SPACED APART RELATION, COOPERATING MEANS ON SAID FRAME, AND SAID CARRYING MEMBERS DESIGNED AND CONSTRUCTED TO MOUNTED SAID CARRYING MEMBERS ON SAID FRAME WHILE ALLOWING LIMITED PIVOTING MOVEMENT OF SAID CARRYING MEMBERS IN RELATION TO SAID FRAME ABOUT AN ACIS PERPENDICULAR TO BUT SPACED FROM THE LONGITUDINAL AXES OF SAID CARRYING MEMBERS IN RESPONSE TO THE IMPOSITION OF LOAD, SAID CARRYING MEMBERS EACH HAVING GRIPPERS, GRIPPER OPERATING MEANS CARRIED BY EACH CARRYING MEMBER, RESPONSIVE TO PIVOTING MOVEMENT OF ITS RESPECTIVE CARRYING MEMBER ABOUT SAID AXIS UNDER LOAD FOR MOVING THE GRIPPERS ON EACH CARRYING MEMBER TOWARDS THE GRIPPERS ON AN ADJA- 